com_android_internal_os_Zygote.cpp revision 0fabba396fe2ff0be864ea6c6a1ed8030ce5de7d
1/* 2 * Copyright (C) 2008 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17#define LOG_TAG "Zygote" 18 19// sys/mount.h has to come before linux/fs.h due to redefinition of MS_RDONLY, MS_BIND, etc 20#include <sys/mount.h> 21#include <linux/fs.h> 22 23#include <list> 24#include <sstream> 25#include <string> 26 27#include <fcntl.h> 28#include <grp.h> 29#include <inttypes.h> 30#include <mntent.h> 31#include <paths.h> 32#include <signal.h> 33#include <stdlib.h> 34#include <sys/capability.h> 35#include <sys/cdefs.h> 36#include <sys/personality.h> 37#include <sys/prctl.h> 38#include <sys/resource.h> 39#include <sys/stat.h> 40#include <sys/time.h> 41#include <sys/types.h> 42#include <sys/utsname.h> 43#include <sys/wait.h> 44#include <unistd.h> 45 46#include "android-base/logging.h" 47#include <cutils/fs.h> 48#include <cutils/multiuser.h> 49#include <cutils/sched_policy.h> 50#include <private/android_filesystem_config.h> 51#include <utils/String8.h> 52#include <selinux/android.h> 53#include <processgroup/processgroup.h> 54 55#include "core_jni_helpers.h" 56#include "JNIHelp.h" 57#include "ScopedLocalRef.h" 58#include "ScopedPrimitiveArray.h" 59#include "ScopedUtfChars.h" 60#include "fd_utils.h" 61 62#include "nativebridge/native_bridge.h" 63 64namespace { 65 66using android::String8; 67 68static pid_t gSystemServerPid = 0; 69 70static const char kZygoteClassName[] = "com/android/internal/os/Zygote"; 71static jclass gZygoteClass; 72static jmethodID gCallPostForkChildHooks; 73 74// Must match values in com.android.internal.os.Zygote. 75enum MountExternalKind { 76 MOUNT_EXTERNAL_NONE = 0, 77 MOUNT_EXTERNAL_DEFAULT = 1, 78 MOUNT_EXTERNAL_READ = 2, 79 MOUNT_EXTERNAL_WRITE = 3, 80}; 81 82static void RuntimeAbort(JNIEnv* env, int line, const char* msg) { 83 std::ostringstream oss; 84 oss << __FILE__ << ":" << line << ": " << msg; 85 env->FatalError(oss.str().c_str()); 86} 87 88// This signal handler is for zygote mode, since the zygote must reap its children 89static void SigChldHandler(int /*signal_number*/) { 90 pid_t pid; 91 int status; 92 93 // It's necessary to save and restore the errno during this function. 94 // Since errno is stored per thread, changing it here modifies the errno 95 // on the thread on which this signal handler executes. If a signal occurs 96 // between a call and an errno check, it's possible to get the errno set 97 // here. 98 // See b/23572286 for extra information. 99 int saved_errno = errno; 100 101 while ((pid = waitpid(-1, &status, WNOHANG)) > 0) { 102 // Log process-death status that we care about. In general it is 103 // not safe to call LOG(...) from a signal handler because of 104 // possible reentrancy. However, we know a priori that the 105 // current implementation of LOG() is safe to call from a SIGCHLD 106 // handler in the zygote process. If the LOG() implementation 107 // changes its locking strategy or its use of syscalls within the 108 // lazy-init critical section, its use here may become unsafe. 109 if (WIFEXITED(status)) { 110 if (WEXITSTATUS(status)) { 111 ALOGI("Process %d exited cleanly (%d)", pid, WEXITSTATUS(status)); 112 } 113 } else if (WIFSIGNALED(status)) { 114 if (WTERMSIG(status) != SIGKILL) { 115 ALOGI("Process %d exited due to signal (%d)", pid, WTERMSIG(status)); 116 } 117 if (WCOREDUMP(status)) { 118 ALOGI("Process %d dumped core.", pid); 119 } 120 } 121 122 // If the just-crashed process is the system_server, bring down zygote 123 // so that it is restarted by init and system server will be restarted 124 // from there. 125 if (pid == gSystemServerPid) { 126 ALOGE("Exit zygote because system server (%d) has terminated", pid); 127 kill(getpid(), SIGKILL); 128 } 129 } 130 131 // Note that we shouldn't consider ECHILD an error because 132 // the secondary zygote might have no children left to wait for. 133 if (pid < 0 && errno != ECHILD) { 134 ALOGW("Zygote SIGCHLD error in waitpid: %s", strerror(errno)); 135 } 136 137 errno = saved_errno; 138} 139 140// Configures the SIGCHLD handler for the zygote process. This is configured 141// very late, because earlier in the runtime we may fork() and exec() 142// other processes, and we want to waitpid() for those rather than 143// have them be harvested immediately. 144// 145// This ends up being called repeatedly before each fork(), but there's 146// no real harm in that. 147static void SetSigChldHandler() { 148 struct sigaction sa; 149 memset(&sa, 0, sizeof(sa)); 150 sa.sa_handler = SigChldHandler; 151 152 int err = sigaction(SIGCHLD, &sa, NULL); 153 if (err < 0) { 154 ALOGW("Error setting SIGCHLD handler: %s", strerror(errno)); 155 } 156} 157 158// Sets the SIGCHLD handler back to default behavior in zygote children. 159static void UnsetSigChldHandler() { 160 struct sigaction sa; 161 memset(&sa, 0, sizeof(sa)); 162 sa.sa_handler = SIG_DFL; 163 164 int err = sigaction(SIGCHLD, &sa, NULL); 165 if (err < 0) { 166 ALOGW("Error unsetting SIGCHLD handler: %s", strerror(errno)); 167 } 168} 169 170// Calls POSIX setgroups() using the int[] object as an argument. 171// A NULL argument is tolerated. 172static void SetGids(JNIEnv* env, jintArray javaGids) { 173 if (javaGids == NULL) { 174 return; 175 } 176 177 ScopedIntArrayRO gids(env, javaGids); 178 if (gids.get() == NULL) { 179 RuntimeAbort(env, __LINE__, "Getting gids int array failed"); 180 } 181 int rc = setgroups(gids.size(), reinterpret_cast<const gid_t*>(&gids[0])); 182 if (rc == -1) { 183 std::ostringstream oss; 184 oss << "setgroups failed: " << strerror(errno) << ", gids.size=" << gids.size(); 185 RuntimeAbort(env, __LINE__, oss.str().c_str()); 186 } 187} 188 189// Sets the resource limits via setrlimit(2) for the values in the 190// two-dimensional array of integers that's passed in. The second dimension 191// contains a tuple of length 3: (resource, rlim_cur, rlim_max). NULL is 192// treated as an empty array. 193static void SetRLimits(JNIEnv* env, jobjectArray javaRlimits) { 194 if (javaRlimits == NULL) { 195 return; 196 } 197 198 rlimit rlim; 199 memset(&rlim, 0, sizeof(rlim)); 200 201 for (int i = 0; i < env->GetArrayLength(javaRlimits); ++i) { 202 ScopedLocalRef<jobject> javaRlimitObject(env, env->GetObjectArrayElement(javaRlimits, i)); 203 ScopedIntArrayRO javaRlimit(env, reinterpret_cast<jintArray>(javaRlimitObject.get())); 204 if (javaRlimit.size() != 3) { 205 RuntimeAbort(env, __LINE__, "rlimits array must have a second dimension of size 3"); 206 } 207 208 rlim.rlim_cur = javaRlimit[1]; 209 rlim.rlim_max = javaRlimit[2]; 210 211 int rc = setrlimit(javaRlimit[0], &rlim); 212 if (rc == -1) { 213 ALOGE("setrlimit(%d, {%ld, %ld}) failed", javaRlimit[0], rlim.rlim_cur, 214 rlim.rlim_max); 215 RuntimeAbort(env, __LINE__, "setrlimit failed"); 216 } 217 } 218} 219 220// The debug malloc library needs to know whether it's the zygote or a child. 221extern "C" int gMallocLeakZygoteChild; 222 223static void EnableKeepCapabilities(JNIEnv* env) { 224 int rc = prctl(PR_SET_KEEPCAPS, 1, 0, 0, 0); 225 if (rc == -1) { 226 RuntimeAbort(env, __LINE__, "prctl(PR_SET_KEEPCAPS) failed"); 227 } 228} 229 230static void DropCapabilitiesBoundingSet(JNIEnv* env) { 231 for (int i = 0; prctl(PR_CAPBSET_READ, i, 0, 0, 0) >= 0; i++) { 232 int rc = prctl(PR_CAPBSET_DROP, i, 0, 0, 0); 233 if (rc == -1) { 234 if (errno == EINVAL) { 235 ALOGE("prctl(PR_CAPBSET_DROP) failed with EINVAL. Please verify " 236 "your kernel is compiled with file capabilities support"); 237 } else { 238 ALOGE("prctl(PR_CAPBSET_DROP, %d) failed: %s", i, strerror(errno)); 239 RuntimeAbort(env, __LINE__, "prctl(PR_CAPBSET_DROP) failed"); 240 } 241 } 242 } 243} 244 245static void SetInheritable(JNIEnv* env, uint64_t inheritable) { 246 __user_cap_header_struct capheader; 247 memset(&capheader, 0, sizeof(capheader)); 248 capheader.version = _LINUX_CAPABILITY_VERSION_3; 249 capheader.pid = 0; 250 251 __user_cap_data_struct capdata[2]; 252 if (capget(&capheader, &capdata[0]) == -1) { 253 ALOGE("capget failed: %s", strerror(errno)); 254 RuntimeAbort(env, __LINE__, "capget failed"); 255 } 256 257 capdata[0].inheritable = inheritable; 258 capdata[1].inheritable = inheritable >> 32; 259 260 if (capset(&capheader, &capdata[0]) == -1) { 261 ALOGE("capset(inh=%" PRIx64 ") failed: %s", inheritable, strerror(errno)); 262 RuntimeAbort(env, __LINE__, "capset failed"); 263 } 264} 265 266static void SetCapabilities(JNIEnv* env, uint64_t permitted, uint64_t effective, 267 uint64_t inheritable) { 268 __user_cap_header_struct capheader; 269 memset(&capheader, 0, sizeof(capheader)); 270 capheader.version = _LINUX_CAPABILITY_VERSION_3; 271 capheader.pid = 0; 272 273 __user_cap_data_struct capdata[2]; 274 memset(&capdata, 0, sizeof(capdata)); 275 capdata[0].effective = effective; 276 capdata[1].effective = effective >> 32; 277 capdata[0].permitted = permitted; 278 capdata[1].permitted = permitted >> 32; 279 capdata[0].inheritable = inheritable; 280 capdata[1].inheritable = inheritable >> 32; 281 282 if (capset(&capheader, &capdata[0]) == -1) { 283 ALOGE("capset(perm=%" PRIx64 ", eff=%" PRIx64 ", inh=%" PRIx64 ") failed: %s", permitted, 284 effective, inheritable, strerror(errno)); 285 RuntimeAbort(env, __LINE__, "capset failed"); 286 } 287} 288 289static void SetSchedulerPolicy(JNIEnv* env) { 290 errno = -set_sched_policy(0, SP_DEFAULT); 291 if (errno != 0) { 292 ALOGE("set_sched_policy(0, SP_DEFAULT) failed"); 293 RuntimeAbort(env, __LINE__, "set_sched_policy(0, SP_DEFAULT) failed"); 294 } 295} 296 297static int UnmountTree(const char* path) { 298 size_t path_len = strlen(path); 299 300 FILE* fp = setmntent("/proc/mounts", "r"); 301 if (fp == NULL) { 302 ALOGE("Error opening /proc/mounts: %s", strerror(errno)); 303 return -errno; 304 } 305 306 // Some volumes can be stacked on each other, so force unmount in 307 // reverse order to give us the best chance of success. 308 std::list<std::string> toUnmount; 309 mntent* mentry; 310 while ((mentry = getmntent(fp)) != NULL) { 311 if (strncmp(mentry->mnt_dir, path, path_len) == 0) { 312 toUnmount.push_front(std::string(mentry->mnt_dir)); 313 } 314 } 315 endmntent(fp); 316 317 for (auto path : toUnmount) { 318 if (umount2(path.c_str(), MNT_DETACH)) { 319 ALOGW("Failed to unmount %s: %s", path.c_str(), strerror(errno)); 320 } 321 } 322 return 0; 323} 324 325// Create a private mount namespace and bind mount appropriate emulated 326// storage for the given user. 327static bool MountEmulatedStorage(uid_t uid, jint mount_mode, 328 bool force_mount_namespace) { 329 // See storage config details at http://source.android.com/tech/storage/ 330 331 String8 storageSource; 332 if (mount_mode == MOUNT_EXTERNAL_DEFAULT) { 333 storageSource = "/mnt/runtime/default"; 334 } else if (mount_mode == MOUNT_EXTERNAL_READ) { 335 storageSource = "/mnt/runtime/read"; 336 } else if (mount_mode == MOUNT_EXTERNAL_WRITE) { 337 storageSource = "/mnt/runtime/write"; 338 } else if (!force_mount_namespace) { 339 // Sane default of no storage visible 340 return true; 341 } 342 343 // Create a second private mount namespace for our process 344 if (unshare(CLONE_NEWNS) == -1) { 345 ALOGW("Failed to unshare(): %s", strerror(errno)); 346 return false; 347 } 348 349 // Handle force_mount_namespace with MOUNT_EXTERNAL_NONE. 350 if (mount_mode == MOUNT_EXTERNAL_NONE) { 351 return true; 352 } 353 354 if (TEMP_FAILURE_RETRY(mount(storageSource.string(), "/storage", 355 NULL, MS_BIND | MS_REC | MS_SLAVE, NULL)) == -1) { 356 ALOGW("Failed to mount %s to /storage: %s", storageSource.string(), strerror(errno)); 357 return false; 358 } 359 360 // Mount user-specific symlink helper into place 361 userid_t user_id = multiuser_get_user_id(uid); 362 const String8 userSource(String8::format("/mnt/user/%d", user_id)); 363 if (fs_prepare_dir(userSource.string(), 0751, 0, 0) == -1) { 364 return false; 365 } 366 if (TEMP_FAILURE_RETRY(mount(userSource.string(), "/storage/self", 367 NULL, MS_BIND, NULL)) == -1) { 368 ALOGW("Failed to mount %s to /storage/self: %s", userSource.string(), strerror(errno)); 369 return false; 370 } 371 372 return true; 373} 374 375static bool NeedsNoRandomizeWorkaround() { 376#if !defined(__arm__) 377 return false; 378#else 379 int major; 380 int minor; 381 struct utsname uts; 382 if (uname(&uts) == -1) { 383 return false; 384 } 385 386 if (sscanf(uts.release, "%d.%d", &major, &minor) != 2) { 387 return false; 388 } 389 390 // Kernels before 3.4.* need the workaround. 391 return (major < 3) || ((major == 3) && (minor < 4)); 392#endif 393} 394 395// Utility to close down the Zygote socket file descriptors while 396// the child is still running as root with Zygote's privileges. Each 397// descriptor (if any) is closed via dup2(), replacing it with a valid 398// (open) descriptor to /dev/null. 399 400static void DetachDescriptors(JNIEnv* env, jintArray fdsToClose) { 401 if (!fdsToClose) { 402 return; 403 } 404 jsize count = env->GetArrayLength(fdsToClose); 405 ScopedIntArrayRO ar(env, fdsToClose); 406 if (ar.get() == NULL) { 407 RuntimeAbort(env, __LINE__, "Bad fd array"); 408 } 409 jsize i; 410 int devnull; 411 for (i = 0; i < count; i++) { 412 devnull = open("/dev/null", O_RDWR); 413 if (devnull < 0) { 414 ALOGE("Failed to open /dev/null: %s", strerror(errno)); 415 RuntimeAbort(env, __LINE__, "Failed to open /dev/null"); 416 continue; 417 } 418 ALOGV("Switching descriptor %d to /dev/null: %s", ar[i], strerror(errno)); 419 if (dup2(devnull, ar[i]) < 0) { 420 ALOGE("Failed dup2() on descriptor %d: %s", ar[i], strerror(errno)); 421 RuntimeAbort(env, __LINE__, "Failed dup2()"); 422 } 423 close(devnull); 424 } 425} 426 427void SetThreadName(const char* thread_name) { 428 bool hasAt = false; 429 bool hasDot = false; 430 const char* s = thread_name; 431 while (*s) { 432 if (*s == '.') { 433 hasDot = true; 434 } else if (*s == '@') { 435 hasAt = true; 436 } 437 s++; 438 } 439 const int len = s - thread_name; 440 if (len < 15 || hasAt || !hasDot) { 441 s = thread_name; 442 } else { 443 s = thread_name + len - 15; 444 } 445 // pthread_setname_np fails rather than truncating long strings. 446 char buf[16]; // MAX_TASK_COMM_LEN=16 is hard-coded into bionic 447 strlcpy(buf, s, sizeof(buf)-1); 448 errno = pthread_setname_np(pthread_self(), buf); 449 if (errno != 0) { 450 ALOGW("Unable to set the name of current thread to '%s': %s", buf, strerror(errno)); 451 } 452} 453 454// The list of open zygote file descriptors. 455static FileDescriptorTable* gOpenFdTable = NULL; 456 457static void FillFileDescriptorVector(JNIEnv* env, 458 jintArray java_fds, 459 std::vector<int>* fds) { 460 CHECK(fds != nullptr); 461 if (java_fds != nullptr) { 462 ScopedIntArrayRO ar(env, java_fds); 463 if (ar.get() == nullptr) { 464 RuntimeAbort(env, __LINE__, "Bad fd array"); 465 } 466 fds->reserve(ar.size()); 467 for (size_t i = 0; i < ar.size(); ++i) { 468 fds->push_back(ar[i]); 469 } 470 } 471} 472 473// Utility routine to fork zygote and specialize the child process. 474static pid_t ForkAndSpecializeCommon(JNIEnv* env, uid_t uid, gid_t gid, jintArray javaGids, 475 jint debug_flags, jobjectArray javaRlimits, 476 jlong permittedCapabilities, jlong effectiveCapabilities, 477 jint mount_external, 478 jstring java_se_info, jstring java_se_name, 479 bool is_system_server, jintArray fdsToClose, 480 jintArray fdsToIgnore, 481 jstring instructionSet, jstring dataDir) { 482 SetSigChldHandler(); 483 484 sigset_t sigchld; 485 sigemptyset(&sigchld); 486 sigaddset(&sigchld, SIGCHLD); 487 488 // Temporarily block SIGCHLD during forks. The SIGCHLD handler might 489 // log, which would result in the logging FDs we close being reopened. 490 // This would cause failures because the FDs are not whitelisted. 491 // 492 // Note that the zygote process is single threaded at this point. 493 if (sigprocmask(SIG_BLOCK, &sigchld, nullptr) == -1) { 494 ALOGE("sigprocmask(SIG_SETMASK, { SIGCHLD }) failed: %s", strerror(errno)); 495 RuntimeAbort(env, __LINE__, "Call to sigprocmask(SIG_BLOCK, { SIGCHLD }) failed."); 496 } 497 498 // Close any logging related FDs before we start evaluating the list of 499 // file descriptors. 500 __android_log_close(); 501 502 // If this is the first fork for this zygote, create the open FD table. 503 // If it isn't, we just need to check whether the list of open files has 504 // changed (and it shouldn't in the normal case). 505 std::vector<int> fds_to_ignore; 506 FillFileDescriptorVector(env, fdsToIgnore, &fds_to_ignore); 507 if (gOpenFdTable == NULL) { 508 gOpenFdTable = FileDescriptorTable::Create(fds_to_ignore); 509 if (gOpenFdTable == NULL) { 510 RuntimeAbort(env, __LINE__, "Unable to construct file descriptor table."); 511 } 512 } else if (!gOpenFdTable->Restat(fds_to_ignore)) { 513 RuntimeAbort(env, __LINE__, "Unable to restat file descriptor table."); 514 } 515 516 pid_t pid = fork(); 517 518 if (pid == 0) { 519 // The child process. 520 gMallocLeakZygoteChild = 1; 521 522 // Clean up any descriptors which must be closed immediately 523 DetachDescriptors(env, fdsToClose); 524 525 // Re-open all remaining open file descriptors so that they aren't shared 526 // with the zygote across a fork. 527 if (!gOpenFdTable->ReopenOrDetach()) { 528 RuntimeAbort(env, __LINE__, "Unable to reopen whitelisted descriptors."); 529 } 530 531 if (sigprocmask(SIG_UNBLOCK, &sigchld, nullptr) == -1) { 532 ALOGE("sigprocmask(SIG_SETMASK, { SIGCHLD }) failed: %s", strerror(errno)); 533 RuntimeAbort(env, __LINE__, "Call to sigprocmask(SIG_UNBLOCK, { SIGCHLD }) failed."); 534 } 535 536 // Keep capabilities across UID change, unless we're staying root. 537 if (uid != 0) { 538 EnableKeepCapabilities(env); 539 } 540 541 SetInheritable(env, permittedCapabilities); 542 DropCapabilitiesBoundingSet(env); 543 544 bool use_native_bridge = !is_system_server && (instructionSet != NULL) 545 && android::NativeBridgeAvailable(); 546 if (use_native_bridge) { 547 ScopedUtfChars isa_string(env, instructionSet); 548 use_native_bridge = android::NeedsNativeBridge(isa_string.c_str()); 549 } 550 if (use_native_bridge && dataDir == NULL) { 551 // dataDir should never be null if we need to use a native bridge. 552 // In general, dataDir will never be null for normal applications. It can only happen in 553 // special cases (for isolated processes which are not associated with any app). These are 554 // launched by the framework and should not be emulated anyway. 555 use_native_bridge = false; 556 ALOGW("Native bridge will not be used because dataDir == NULL."); 557 } 558 559 if (!MountEmulatedStorage(uid, mount_external, use_native_bridge)) { 560 ALOGW("Failed to mount emulated storage: %s", strerror(errno)); 561 if (errno == ENOTCONN || errno == EROFS) { 562 // When device is actively encrypting, we get ENOTCONN here 563 // since FUSE was mounted before the framework restarted. 564 // When encrypted device is booting, we get EROFS since 565 // FUSE hasn't been created yet by init. 566 // In either case, continue without external storage. 567 } else { 568 RuntimeAbort(env, __LINE__, "Cannot continue without emulated storage"); 569 } 570 } 571 572 if (!is_system_server) { 573 int rc = createProcessGroup(uid, getpid()); 574 if (rc != 0) { 575 if (rc == -EROFS) { 576 ALOGW("createProcessGroup failed, kernel missing CONFIG_CGROUP_CPUACCT?"); 577 } else { 578 ALOGE("createProcessGroup(%d, %d) failed: %s", uid, pid, strerror(-rc)); 579 } 580 } 581 } 582 583 SetGids(env, javaGids); 584 585 SetRLimits(env, javaRlimits); 586 587 if (use_native_bridge) { 588 ScopedUtfChars isa_string(env, instructionSet); 589 ScopedUtfChars data_dir(env, dataDir); 590 android::PreInitializeNativeBridge(data_dir.c_str(), isa_string.c_str()); 591 } 592 593 int rc = setresgid(gid, gid, gid); 594 if (rc == -1) { 595 ALOGE("setresgid(%d) failed: %s", gid, strerror(errno)); 596 RuntimeAbort(env, __LINE__, "setresgid failed"); 597 } 598 599 rc = setresuid(uid, uid, uid); 600 if (rc == -1) { 601 ALOGE("setresuid(%d) failed: %s", uid, strerror(errno)); 602 RuntimeAbort(env, __LINE__, "setresuid failed"); 603 } 604 605 if (NeedsNoRandomizeWorkaround()) { 606 // Work around ARM kernel ASLR lossage (http://b/5817320). 607 int old_personality = personality(0xffffffff); 608 int new_personality = personality(old_personality | ADDR_NO_RANDOMIZE); 609 if (new_personality == -1) { 610 ALOGW("personality(%d) failed: %s", new_personality, strerror(errno)); 611 } 612 } 613 614 SetCapabilities(env, permittedCapabilities, effectiveCapabilities, permittedCapabilities); 615 616 SetSchedulerPolicy(env); 617 618 const char* se_info_c_str = NULL; 619 ScopedUtfChars* se_info = NULL; 620 if (java_se_info != NULL) { 621 se_info = new ScopedUtfChars(env, java_se_info); 622 se_info_c_str = se_info->c_str(); 623 if (se_info_c_str == NULL) { 624 RuntimeAbort(env, __LINE__, "se_info_c_str == NULL"); 625 } 626 } 627 const char* se_name_c_str = NULL; 628 ScopedUtfChars* se_name = NULL; 629 if (java_se_name != NULL) { 630 se_name = new ScopedUtfChars(env, java_se_name); 631 se_name_c_str = se_name->c_str(); 632 if (se_name_c_str == NULL) { 633 RuntimeAbort(env, __LINE__, "se_name_c_str == NULL"); 634 } 635 } 636 rc = selinux_android_setcontext(uid, is_system_server, se_info_c_str, se_name_c_str); 637 if (rc == -1) { 638 ALOGE("selinux_android_setcontext(%d, %d, \"%s\", \"%s\") failed", uid, 639 is_system_server, se_info_c_str, se_name_c_str); 640 RuntimeAbort(env, __LINE__, "selinux_android_setcontext failed"); 641 } 642 643 // Make it easier to debug audit logs by setting the main thread's name to the 644 // nice name rather than "app_process". 645 if (se_info_c_str == NULL && is_system_server) { 646 se_name_c_str = "system_server"; 647 } 648 if (se_info_c_str != NULL) { 649 SetThreadName(se_name_c_str); 650 } 651 652 delete se_info; 653 delete se_name; 654 655 UnsetSigChldHandler(); 656 657 env->CallStaticVoidMethod(gZygoteClass, gCallPostForkChildHooks, debug_flags, 658 is_system_server, instructionSet); 659 if (env->ExceptionCheck()) { 660 RuntimeAbort(env, __LINE__, "Error calling post fork hooks."); 661 } 662 } else if (pid > 0) { 663 // the parent process 664 665 // We blocked SIGCHLD prior to a fork, we unblock it here. 666 if (sigprocmask(SIG_UNBLOCK, &sigchld, nullptr) == -1) { 667 ALOGE("sigprocmask(SIG_SETMASK, { SIGCHLD }) failed: %s", strerror(errno)); 668 RuntimeAbort(env, __LINE__, "Call to sigprocmask(SIG_UNBLOCK, { SIGCHLD }) failed."); 669 } 670 } 671 return pid; 672} 673} // anonymous namespace 674 675namespace android { 676 677static jint com_android_internal_os_Zygote_nativeForkAndSpecialize( 678 JNIEnv* env, jclass, jint uid, jint gid, jintArray gids, 679 jint debug_flags, jobjectArray rlimits, 680 jint mount_external, jstring se_info, jstring se_name, 681 jintArray fdsToClose, 682 jintArray fdsToIgnore, 683 jstring instructionSet, jstring appDataDir) { 684 jlong capabilities = 0; 685 686 // Grant CAP_WAKE_ALARM to the Bluetooth process. 687 // Additionally, allow bluetooth to open packet sockets so it can start the DHCP client. 688 // Grant CAP_SYS_NICE to allow Bluetooth to set RT priority for 689 // audio-related threads. 690 // TODO: consider making such functionality an RPC to netd. 691 if (multiuser_get_app_id(uid) == AID_BLUETOOTH) { 692 capabilities |= (1LL << CAP_WAKE_ALARM); 693 capabilities |= (1LL << CAP_NET_RAW); 694 capabilities |= (1LL << CAP_NET_BIND_SERVICE); 695 capabilities |= (1LL << CAP_SYS_NICE); 696 } 697 698 // Grant CAP_BLOCK_SUSPEND to processes that belong to GID "wakelock" 699 bool gid_wakelock_found = false; 700 if (gid == AID_WAKELOCK) { 701 gid_wakelock_found = true; 702 } else if (gids != NULL) { 703 jsize gids_num = env->GetArrayLength(gids); 704 ScopedIntArrayRO ar(env, gids); 705 if (ar.get() == NULL) { 706 RuntimeAbort(env, __LINE__, "Bad gids array"); 707 } 708 for (int i = 0; i < gids_num; i++) { 709 if (ar[i] == AID_WAKELOCK) { 710 gid_wakelock_found = true; 711 break; 712 } 713 } 714 } 715 if (gid_wakelock_found) { 716 capabilities |= (1LL << CAP_BLOCK_SUSPEND); 717 } 718 719 return ForkAndSpecializeCommon(env, uid, gid, gids, debug_flags, 720 rlimits, capabilities, capabilities, mount_external, se_info, 721 se_name, false, fdsToClose, fdsToIgnore, instructionSet, appDataDir); 722} 723 724static jint com_android_internal_os_Zygote_nativeForkSystemServer( 725 JNIEnv* env, jclass, uid_t uid, gid_t gid, jintArray gids, 726 jint debug_flags, jobjectArray rlimits, jlong permittedCapabilities, 727 jlong effectiveCapabilities) { 728 pid_t pid = ForkAndSpecializeCommon(env, uid, gid, gids, 729 debug_flags, rlimits, 730 permittedCapabilities, effectiveCapabilities, 731 MOUNT_EXTERNAL_DEFAULT, NULL, NULL, true, NULL, 732 NULL, NULL, NULL); 733 if (pid > 0) { 734 // The zygote process checks whether the child process has died or not. 735 ALOGI("System server process %d has been created", pid); 736 gSystemServerPid = pid; 737 // There is a slight window that the system server process has crashed 738 // but it went unnoticed because we haven't published its pid yet. So 739 // we recheck here just to make sure that all is well. 740 int status; 741 if (waitpid(pid, &status, WNOHANG) == pid) { 742 ALOGE("System server process %d has died. Restarting Zygote!", pid); 743 RuntimeAbort(env, __LINE__, "System server process has died. Restarting Zygote!"); 744 } 745 } 746 return pid; 747} 748 749static void com_android_internal_os_Zygote_nativeAllowFileAcrossFork( 750 JNIEnv* env, jclass, jstring path) { 751 ScopedUtfChars path_native(env, path); 752 const char* path_cstr = path_native.c_str(); 753 if (!path_cstr) { 754 RuntimeAbort(env, __LINE__, "path_cstr == NULL"); 755 } 756 FileDescriptorWhitelist::Get()->Allow(path_cstr); 757} 758 759static void com_android_internal_os_Zygote_nativeUnmountStorageOnInit(JNIEnv* env, jclass) { 760 // Zygote process unmount root storage space initially before every child processes are forked. 761 // Every forked child processes (include SystemServer) only mount their own root storage space 762 // and no need unmount storage operation in MountEmulatedStorage method. 763 // Zygote process does not utilize root storage spaces and unshares its mount namespace below. 764 765 // See storage config details at http://source.android.com/tech/storage/ 766 // Create private mount namespace shared by all children 767 if (unshare(CLONE_NEWNS) == -1) { 768 RuntimeAbort(env, __LINE__, "Failed to unshare()"); 769 return; 770 } 771 772 // Mark rootfs as being a slave so that changes from default 773 // namespace only flow into our children. 774 if (mount("rootfs", "/", nullptr, (MS_SLAVE | MS_REC), nullptr) == -1) { 775 RuntimeAbort(env, __LINE__, "Failed to mount() rootfs as MS_SLAVE"); 776 return; 777 } 778 779 // Create a staging tmpfs that is shared by our children; they will 780 // bind mount storage into their respective private namespaces, which 781 // are isolated from each other. 782 const char* target_base = getenv("EMULATED_STORAGE_TARGET"); 783 if (target_base != nullptr) { 784#define STRINGIFY_UID(x) __STRING(x) 785 if (mount("tmpfs", target_base, "tmpfs", MS_NOSUID | MS_NODEV, 786 "uid=0,gid=" STRINGIFY_UID(AID_SDCARD_R) ",mode=0751") == -1) { 787 ALOGE("Failed to mount tmpfs to %s", target_base); 788 RuntimeAbort(env, __LINE__, "Failed to mount tmpfs"); 789 return; 790 } 791#undef STRINGIFY_UID 792 } 793 794 UnmountTree("/storage"); 795} 796 797static const JNINativeMethod gMethods[] = { 798 { "nativeForkAndSpecialize", 799 "(II[II[[IILjava/lang/String;Ljava/lang/String;[I[ILjava/lang/String;Ljava/lang/String;)I", 800 (void *) com_android_internal_os_Zygote_nativeForkAndSpecialize }, 801 { "nativeForkSystemServer", "(II[II[[IJJ)I", 802 (void *) com_android_internal_os_Zygote_nativeForkSystemServer }, 803 { "nativeAllowFileAcrossFork", "(Ljava/lang/String;)V", 804 (void *) com_android_internal_os_Zygote_nativeAllowFileAcrossFork }, 805 { "nativeUnmountStorageOnInit", "()V", 806 (void *) com_android_internal_os_Zygote_nativeUnmountStorageOnInit } 807}; 808 809int register_com_android_internal_os_Zygote(JNIEnv* env) { 810 gZygoteClass = MakeGlobalRefOrDie(env, FindClassOrDie(env, kZygoteClassName)); 811 gCallPostForkChildHooks = GetStaticMethodIDOrDie(env, gZygoteClass, "callPostForkChildHooks", 812 "(IZLjava/lang/String;)V"); 813 814 return RegisterMethodsOrDie(env, "com/android/internal/os/Zygote", gMethods, NELEM(gMethods)); 815} 816} // namespace android 817